ML20012B410

Discusses NRC 900221 Granting of Discretionary Enforcement to Continue Shutdown Cooling Operation Until Reactor Level Instrument 1B21-N080A Can Be Returned to Svc.Replacement Expected to Be Completed by 900222

ML20012B410
Person / Time
Site:	Hatch
Issue date:	02/22/1990
From:	Hairston W GEORGIA POWER CO.
To:	Ebneter S NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
HL-983, NUDOCS 9003140352
Download: ML20012B410 (3)

Text

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. U.S. Nuclear Regulatory Commission ATTN:- Mr. S. D.-Ebneter Regional Administrator - Region II

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0 PLANT HATCH - UNIT 1  ;

NRC DOCKET 50-321 OPERATING LICENSE DPR-57

' DISCRETIONARY ENFORCEMENT REGARDING RHR SHUTDOHN COOLING Gentlemen:

On February 21, 1990,.- in a conversation -between representatives of .

Georgia Power Company (GPC), .NRC-Region. II, and NRC-Nuclear Reactor- "

Regulation (NRR), GPC requested -temporary relief from the requirements of Unit' 1 , Technical Specifications -(TS) . Table 3.2-1, item 1.

This-

.-discretion was needed to allow - continued operation- of.the Residual ' Heat.

-Removal: (RHR): System in the shutdown cooling _ (SDC) mode until an

. inoperable reactor water level instrument could be replaced. The NRC based their decision. to grant- discretionary enforcement _on the a information discussed during the phone call, and confirmed.it via another

telephone conversation with GPC later the same day.  !

Plant Hatch Unit I shut down on 2/17/90 for a: scheduled condenser -

2-retubing 'and refueling outage. The RHR system is routinely:used in' the SDC mode to remove decay and sensible heat from the fuel /ves' s el prior to '

defueling.. In ' the SDC ~ mode the RHR -System takes suction from the "B" .

,  : recirculation loop,. cools the primary system fluid by passing it through i an RHR heat' exchanger, and then discharges the water back to .the vessel.

, Because ' the- piping represents a potential flow path for draining ' the

' ,s vessel, the' suction side piping is equipped with tv- isolation valves  !

(1E11-F008, F009) which close automatically on low reactor water level (Level 3).

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U.S. Nuclear Regulatory Commission February 22, 1990 Page Two During performance of an 18-month calibration, one reactor water '

level transmitter (IB21-N080A) was found to be out of procedural

tolerance, and efforts to recalibrate the instrument were unsuccessful.

The instrument would still perform its function, but would send an isolation- signal to the valve at a less conservative setpoint than '

speci fied, and was therefore considered inoperable. Unit 1 Technical Specifications (TS) Section 3.2 (Table 3.2-1. Item 1) requires isolation ,

of the SDC System, because there are no longer two operable channels per trip system.- Note that in this situation, Unit 1 TS requirement 3.5.B.1.b conflicts with Table- 3.2-1, in that it requires the RHR SDC mode to-be operable when irradiated fuel is in the vessel.

Representatives from NRR and Region.II agreed that isolation of SDC was not desirable considering the plant configuration. The unit is in cold shutdown with the reactor head removed and the reactor cavity being i filled .in preparation for refueling activities. Current. levels of decay heat..in the fuel could cause reactor- temperature to eventually exceed 212'F which would technically place the unit in an undefined condition.

To preclude' this increase in coolant temperature the decay heat would '

have to be removed by other means. Operation of SDC with one inoperable level instrument does not place the unit in an unsafe condition, since the 5N; isolation function is still single failure proof. The A and C water level transmitters are utilized in the logic of one trip system and either instrument can cause the inboard isolation valve to close.

Likewise, either the B or D transmitter can shut the outboard valve.

Because of. the desire to not isolate SDC and the relatively low '

safety significance of this problem, the NRC granted-verbal discretionary enforcement to continue SDC operation until the reactor level instrument IB21-N080A can be returned to service.

Replacement is expected 'to be

. complete-February 22, 1990.

Please contact this office if you have questions.

Sincerely,

/A W H. G. Hairston, III H

H GKM/eb ci (See next page.)

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Georgia Patyer A U.S. Nuclear Regulat0O Commission

-February 22. 1990 Page Three c: Georaia-Power Comoany Mr. H. C. Nix, General Manager - Nuclear Plant Mr. J. D. Heidt, !ianager Engineering and Licensing - Hatch-GO-NORMS U.S. Nuclear Reaulatory Commission. Hashinaton. D.C. .

Mr. L. P. Crocker, Licensing Project Manager - Hatch

.U.S. Nuclear Regulatory Commission. Region II Mr. J. E. Menning, Senior Resident Inspector - Hatch 1

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